Mary-Kate Olsen and her older, taller, boyfriend Olivier Sarkozy “couldn’t keep their hands off each other” at a MoMA PS1 gala benefit Tuesday, spies said. The couple avoided photographers but then were seen smooching at the gala, which celebrated performance art. Guests including Kim Cattrall and Solange Knowles were led to an upstairs dinner in MoMA’s Marron atrium after cocktails via a “parade” organized by artist Mariah Robertson, where they dined at “an elegant spiral table.”